Create rule S6935: Do not use implicit SYSIN DD * statements (#3685)

rules/S6935/jcl/metadata.json

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+{
+  "title": "Do not use implicit SYSIN DD * statements",
+  "type": "CODE_SMELL",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "1min"
+  },
+  "tags": [
+    "bad-practice"
+  ],
+  "defaultSeverity": "Major",
+  "ruleSpecification": "RSPEC-6935",
+  "sqKey": "S6935",
+  "scope": "All",
+  "defaultQualityProfiles": [],
+  "quickfix": "unknown",
+  "code": {
+    "impacts": {
+      "MAINTAINABILITY": "MEDIUM",
+      "RELIABILITY": "MEDIUM"
+    },
+    "attribute": "COMPLETE"
+  }
+}

rules/S6935/jcl/rule.adoc

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+Input data that is not a JCL statement implicitly generate a `DD *` statement with the name `SYSIN`.
+
+== Why is this an issue?
+
+This behavior is implicit and may lead to confusion or unexpected behavior.
+
+For example, this code:
+[source,jcl]
+----
+//MYDD DD DSN=TEST
+Some in-stream data
+// DD DSN=CONCAT-DD
+----
+
+Gets implicitly transformed into:
+[source,jcl]
+----
+//MYDD DD DSN=TEST
+//SYSIN DD *
+Some in-stream data
+// DD DSN=CONCAT-DD
+----
+So the last DD statement is a concatenation of the implicit `//SYSIN DD *` statement instead of the explicit `//MYDD DD` statement.
+
+== How to fix it
+
+Add explicitly the `//SYSIN DD *` before the in-stream data.
+
+=== Code examples
+
+==== Noncompliant code example
+
+[source,jcl,diff-id=1,diff-type=noncompliant]
+----
+//STEP1     EXEC PGM=SORT
+//SYSOUT   DD   SYSOUT=*
+//SORTIN   DD   DSN=A123456.SORTIN,DISP=SHR
+//SORTOUT  DD   DSN=A123456.SORTOUT,DISP=OLD
+  SORT FIELDS=(1,12,CH,A)
+----
+
+==== Compliant solution
+
+[source,jcl,diff-id=1,diff-type=compliant]
+----
+//STEP1     EXEC PGM=SORT
+//SYSOUT   DD   SYSOUT=*
+//SORTIN   DD   DSN=A123456.SORTIN,DISP=SHR
+//SORTOUT  DD   DSN=A123456.SORTOUT,DISP=OLD
+//SYSIN    DD   *
+  SORT FIELDS=(1,12,CH,A)
+/*
+----
+
+== Resources
+
+=== Documentation
+
+* https://www.ibm.com/docs/en/zos/3.1.0?topic=parameter-location-in-jcl[IBM reference - DD * location in the JCL]

rules/S6935/metadata.json

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+{
+}